Tom Stoffregen monitors an experiment on his computer as the writer plays test subject.

The science of motion sickness

U professor Tom Stoffregen wants to know what causes motion sickness

By Dana Setterholm

August 4, 2006

When he began his research on motion sickness, Tom Stoffregen
thought finding test subjects would be difficult. After all, it's
called motion sickness because it results in headaches, dizziness,
and, often, literally being sick. What kind of people would be
eager to find out what it takes to make them throw up? U students,
it turns out. A lot of them. "Undergraduate students, as a class,
are suicidal," Stoffregen says bluntly. "I'm flooded with
volunteers." He suspects the mass offering of students may have
something to do with misplaced pride. "People think, 'You can't
make me throw up,'" he says. Unfortunately for them, Stoffregen, a
professor in the College of Education and Human Development's
School of Kinesiology, has invested a lot of time and effort into
finding out exactly what brings on motion sickness. And, like an
academic 007, he's got a license to test. Stoffregen's interest in
motion sickness goes back to his childhood, when he was interested
in space flight. He knew some astronauts suffered motion sickness,
and after studying motion in graduate school and working for NASA,
he wanted to find out why. People have been motion sick for
thousands of years, says Stoffregen, conjuring visions of dizzy
Neanderthals and green-faced Vikings, but no one is sure why.
"There's an intuitive assumption that motion sickness is caused by
the inner ear," he says. So far, the only approach to the problem
has been studying how the sensations in the inner ear and eyes are
different in situations when motion sickness results. For example,
when a person is in a car and the eyes report movement but the body
thinks it's stationary. Stoffregen thinks, however, that these
perceptual differences are not what causes motion sickness. After
all, nearly every person on this planet has experienced those
perceptual differences at some point or another, and if we all
reacted by being motion sick, well, let's just say the world would
be a much different place. We'd have to take pilgrimages instead of
planes, for one thing, and the rides at Disneyland would become the
stuff of children's nightmares. But if perceptual differences are
not the cause of motion sickness, then what is? Movement, says
Stoffregen. He measures the movement of people subjected to his
sickness-inducing tests, and "the people who are going to get sick
commence to move in really weird ways," he says, imitating the type
of staggering walk typical after tequila night at the bar. Even
when the subjects are strapped to an upright stretcher, the ones
who feel sick still move a little. "They wriggle," says Stoffregen.
Due to individual differences to sensitivity, only about half of
Stoffregen's test subjects feel sick. Those who don't also don't
wriggle, which makes Stoffregen think that movement is the key
factor behind motion sickness.

People have been motion sick for thousands of
years, says Stoffregen, conjuring visions of dizzy Neanderthals and
green-faced Vikings, but no one is sure why.

Stoffregen has tested his theory extensively in the University's
Human Factors Research Laboratory. His tests are all designed to
make a person feel motion sick, but the test subjects remain
stationary while the scenery around them shifts. In one test, a
room-like structure is set on metal tracks. The subject stands on a
platform as the "room," which has three walls and a ceiling, slides
forward and backward on the tracks. The effect of the moving room
has also been computerized, so a subject can stand in front of a
huge screen and feel the same effects. Stoffregen also has an Xbox
in his lab, which he asks test subjects to play. He doesn't even
need special games. "The games are so realistic now, they can make
people sick," he explains. Being an undergraduate myself (though
not suicidal) it only seemed right to undergo one test. Stoffregen
directed me to the moving room, where he placed a two-by-four board
on the platform before standing me on it. An inch of my flip-flops
extended past each edge of the two-by-four, placing me just
slightly off-balance. The d?cor was hurl-worthy on its own: The
walls and ceiling were covered in white wallpaper veined with blue,
giving the room the air of a huge marble crypt, and the focal piece
was a bland map of the United States that only added to the
atmosphere. Stoffregen told me to focus on the map, then pulled the
room backward a few feet. The map came zooming at my face, and it
felt as if the floor had tilted backward 45 degrees. I took an
involuntary step back (off the two-by-four), certain that I would
fall over otherwise. Test subjects often endure 30 to 40 minutes of
this, Stoffregen said, but 30 seconds was enough for me. No macho
pride here; I fully believed he could make me toss my cookies.
Interestingly enough, Stoffregen says that no one knows why motion
sickness often results in nausea and vomiting. As yet there is no
scientific explanatinon for why seasickness makes you spew,
carsickness makes you blow chunks, roller coasters make you ralph,
or transoceanic flights to Osaka will make your stomach say
sayonara to that sushi. But despite undergoing tests
designed to make people sick, no participants have ever actually
done the technicolor yawn in the lab. "We're interested in how
[motion sickness] begins, not how it ends," Stoffregen says. "No on
has ever thrown up in my lab. And that's a record I'm proud to
keep."